1. Field of the Invention
The present invention relates to a magnetic recording medium for use in magnetic cards, magnetic sheets and magnetic roll papers for such applications as shopping cards including pre-paid cards, retail store cards; financial cards including credit cards, insurance cards; travelling cards including transit passes, tickets; and identification cards including passports, birth certificates and other personal identification cards.
2. Technical Background
The fields of application of consumer cards containing magnetically recorded information have expanded rapidly in recent years, and the uses of such cards are expanding greatly. The basic structure of such magnetic cards comprises a non-magnetic base material and a magnetic layer formed on top of the non-magnetic base material, and the magnetic layer is used to magnetically record proprietary information. It is essential to prevent unlawful uses enabled by copying or altering of the proprietary information on such media, and there have been many methods which are being used to prevent illegal uses of magnetic cards.
Representative examples of counterfeit preventing measures can be divided into two broad categories: the first method is to make reproduction of magnetic information difficult; and the second method is to incorporate a piece of identifier coding data so as to identify counterfeited cards.
The first method is based on making the reproduction of magnetic information difficult, and there are known examples such as providing a multilayer section for magnetic recording in which to hide the correct information, or providing superfluous information to make analysis of the correct information difficult. However, such methods suffer from the disadvantages of complexity of manufacturing, and the requirement for special equipment to read/write the correct information. Furthermore, once the details of the technique of hiding the correct information are discovered, it is not possible to prevent someone skilled in the art to analyze the data, and to easily duplicate the information or to produce a counterfeit product.
The second method is based on including a special identifier codes in the magnetic card, and such a card cannot be put to actual use unless the card is certified to be genuine, even though the card may contain duplicated magnetic information. However, such cards also suffer from disadvantages of difficult manufacturing process, and the requirement of special reading devices for the identifier codes. Also, this type of card has another major disadvantage that it is not possible to prevent unlawful uses of a genuine card in which the proprietary information has been altered.